Screw thread gauge



Sept. 6, 1932. 'w. E. HoKE scREw THREAD GAUGE:7

Filed Feb. 2l 1950 Patented Sept. 6, v1932 UNITED STATES PATENT OFFICE WILLIAM n. HOKE, or BALfrii/ronn, MARYLAND, AssIGNon To DARDELET' THREADLOOK OORPORATION, on NewV YORK, iv. YWA CORPORATION OF DELAWARE.

:i i of the plug at the opposite end of jsonnw THnnAi) GAUGE Application fiieaiebrury 21, l1930. serial Nb. 430,280.

This invention relates to improvements in screw thread gauges, and has for its principal objects to provide a simple and etlicient gauge for testing screw threads,land particularly internal screw threads, as -to accuracy of manufacture with respect to their minor diameter; to provide a simple and ethcient gauge for internal screw threads of the well kno-wn Dardelet type for quickly and accurately gauging their minor diameter or radial displacement of the conoidal thread rib crest locking surface thereof from the thread axis and determining whether the crest size of such threads falls `within a permissible range of plus and minus variation from a standard nominal size. i

Other Objects and advantages of the invention will appear from the following description of the embodiment of the invention illustrated in the accompanying drawing. Y

In the drawing:

Fig. 1 is a view of the gauge in side eleva-f usted for free spinning thereon of a nut to be tested; i

tion and adj Fig. 2 a view showing a Dardelet nut being spun upon the gauge for testing;

Fig. 3 a view showing the gauge and nutl in minor diameter measuring or indicating relation i Fig. 1 a side'view of the nut displacing slide bar of the gauge; and v Fig. 5 a sectional view on the line 55 of Fig. 1.Y

The gauge comprises a main cylindrical plug member 10, arelatively slidable bar' member 11 guided in a Vlongitudinal slot 12 in member 10, said slot extending along one side of member 10 from end to Aend of the latter member. Plug 10 has an external screw thread 13 formed thereon, which thread is the master or diameter gauging thread and extends from the nut entering Yend of the plug to a cylindrical finger grip. portion 14 the plug. Bar 11 is of substantially greater length than the plug so as to project at one end sufficiently beyond the finger grip end of the plug to afford a convenient finger gripon the bar when the opposite end ofthe bar is at or adjacent theV opposite end of the plug.

kThe thickness of bar 11 is such that the bar has a close sliding fit in slot 12, and the width of the bar and depth of slot 12 are such that the Outer `edge of the bar lies within therroot circleV of thread 13 when the bar is in position in the plug.

The Slot i2 nes in a radin piane @ma the i inner edge of the bar is pressedagainst the bottomj of the slot'by a bowedspring 15. One face of bar 11 is undercut throughout the length ofthe bar to form an :outwardly facing ledge 16 slidably engaged under ther middle portion of spring'15, andthe adjacent side wall of slot 12 is formed with a recess affording an inwardly facing ledge'll. under which the Vfree ends of the spring 'are yieldably engaged, the bar having an inclined face portion 18 and the recess having an opposed similarly inclined wall 19 engaging opposite sides of the spring to hold the spring in Contact as describedwithithe ledges 16 and 17. The recess is slightly longer than the distance Vbetween the ends of the bowed spring to permit compression of the j spring in assembling the gaugeelements, and `the end walls 20 of the recess i serve as abutments to prevent material sliding movement of the spring relatively to the plug. The lspring thus serves to frictionally hold the bar in endwise adjusted positionsv ofy the bar and also to prevent accidental separation or disconnection of the bar from the plug by either endwise or radial movement.

Bar 11 is provided at its outer edge'with an integral upstanding nut-displacing tooth or nger 21, of such height as to extend outward beyond the crest of thread 13, and preferably narrower than lthe nut thread groove and of such height as not to contact the root of the nut thread. Finger`21falso preferably has its side faces 21a and 21. which face towardthe ends of the plug inclined both vradially and transversely relatively toV the plug axis to correspond with the lateral inclination and helix angleV of the sidel faces of the rib of the nut thread Vthe gauge/is designed to test, as shown. Y i

Coactive graduations areprovided on the plug and 'bar cooperative to indicatek whether ornot a measured nut or other internal thread is or" nominal minor diameter and/or within a predetermined permissible range of plus and minus deviation front nominal crest size orminor diameter. As shown, these graduations consistof an intermediate nominal'size graduation 22;and two end or plus and minus limit graduations 23 on member 10 extending to one edge of the slot.12 and a single coactive transverse graduation 24 extending across theupper edge ofr bar l1. The series of three graduationsV on plug 10 may be duplicated at the oppositeside of the slot, as shown, if desired, the plug graduations being placed uponY a plane chordal surface 27 iush with the top of thel graduation v`24 is.. slightly outward beyond face of the shallow buttress thread 1 3 in one Y ing of bar 1l endwise 'outside' the tolerance limits for the minor the minus limit graduation, finger face 21b will Vregister with thel steep and narrow side turn j of the thread, lso thatk the nut may be `freely'spun upon thev plug with itsthread rib running loosely at the lowest part Vof the thread groovevof the plug, as indicated in rigs. 1 and 2, until finger 2l is engaged in a turnof the groove of the nut thread. The remaining wider face of thread 13 makes a small angle with the axial line of the thread and slopes inwardly as it approaches the finger gripend of the plug, so that upon slidby thrust upon its projecting end, linger 21 will displacethe nut axially toward the opposite end of the plu until thecrest'surface of the nut thread seats firmly upon the wide conoidal Vcrest diameter gauging'side face of thread 13 as shown in Fig. 3. If the nut thread is of proper nominal minor diameter, graduation 24 will register'with graduation 22. If the nut thread is of acceptable minor diameter, graduation 24 mustlie'between the graduations v23.

, Thread 13 is of the saine pitch as the thread the gauge is designed to test and its minor andA major diameters should preferably'be diameter ofthe thread/,to be gau ed, as shown. In gauging DardeletV ocking threads, th-e wider face of thread 13 should preferably'malre the same angle Withivthe 'thread axis as the locking crest surface of the thread yto be gauged, as shown, this angle being six degrees. In Figs. 2 and 3.a standardvDardelet locking nut 25 isshown en-` gaged with the gauge, and the inclined `locking surface at the crest of the thread rib is designated 26. Y, y

It will be observed that slide bar 11 with its finger 21l isoperative to measure the extent L of displacement from the smaller end of the helical and low angle gaugingY face of thread 13 required to effect a close lit on saidl surface of the crest of the. nut thread, and thatV the bar and finger are manually shiftable to effect the necessary axial displacement of thenut-on theplug if desired. The bar need not 'necessarily be used forfthe latter purpose, however, as the nut will firmly seat on the plug by gravity if the gauge is Lip-ended,

vorInay be Vdisplaceddirectly by the hand. of the operative, and the bar then shifted to gaugeA the nut thread. After the testing advjustmentof the bar is made and the gauge threads of the Dardelet typeas to minor di- Y ameter, comprising-a plug having an external screw thread of the buttress type of. the saine .pitch as thethread to be tested, and minor diameter variation indicating means Aengageable withv one side face ofan vinternal thread screwed uponthe plug andfmountedin the. plugtomove longitudinally/of the plug.

2. A minor diameter gauge for internal Dardelet screwf threads comprising a plug having a threaded portion provided with a longitudinalchannel and with.an external master screw thread of the buttress type the least steep side face of which thread is the gauging face and makesnan angleof six degrees with .the axis ofthe plug, and a bar slidably held in said channelandprovided with an outwardly projecting linger receivable in the groove of an internal Dardelet thread vscrewed upon theplug thread, vand g means on said -bar and. plug for indicating the relation between one edge ofV said gauging face ofthe plug thread and the lseating position of the crest of the internal thread upon said face. l t x 3. A minor diameter :gauge lfor internal Dardelet screw threads comprising a plug provided with a longitudinal channelyand withV an external screw thread of the buttress type the least steep side face of whichl thread makes an angle of six degrees with the axis of the plug, and a bar slidably held in said channel and provided with an outwardly pro- ]ecting finger .receivable in the groove of an-internal Dardelet thread screwed upon the plug. thread, said thread lterminating short of one end of said bar and plug having graduatioiis vbetween saidend .ofthe plug and the thread coactive to indicate whether or not an internal thread seated on said least steep side facey typeand a longitudinal channel, means slidably mounted inv said channel for axially' the plug and channel, and

shifting a nut screwed upon the plug until the crest of the nut thread seats on the least ste-cp side face of the plug thread, and means coactive with said slidable means for indicating whether the nut thread is of acceptable minor diameter. i

5. A minor diameter gauge for internal screw threads comprising an externally threaded plug having a longitudinal channel therein, and a bar slidable endwise in said channel and having a inger projecting outwardly beyond the periphery of the plug between the ends of the plug thread for engaging in the groove of an internal thread screwed upon the plug.

6. A minor diameter gauge for internal screw threads comprising an externally threaded plug having a longitudinal channel therein, and a Abar slidable endwise in said channel and having a finger projecting outwardly beyond the periphery of the plug between the ends of the plug thread for engaging in the groove of an internal thread screw upon the plug; and means yieldably holding the bar against the bottom of said channel. y

7. A minor diameter gauge for internal screw threads comprising an externally threaded plug having a longitudinal channel therein, and a bar slidable endwise in said channel and having a finger projecting outwardly beyond the periphery of the plug between the ends of the plug thread for engaging in the groove of an internal thread screwed upon the plug; and graduations on the bar and plug for indicating predetermined extents of displacement of an internal thread from one side face of the plug thread when an internal thread is in contact with the 4o other side face of the plug thread.

8. A gauge as claimed in claim 2 wherein the bar is longer than the plug to permit hand shifting of the bar from one end of the bar.

9. A gauge as claimed in claim 7 wherein the bar is longer thanv the plug to permit grasping of one end of the bar for endwise adjustments of the bar in the plug.

l0. A minor diameter gauge for internal screw threads comprising a plug having an external master thread of the buttress type,

means mounted on the plug to travel lengthwise of the plug within the root cylinder of the master thread and carrying a projection which is engageable with one side face of an internal thread screwed on the master thread, and means on said plug and said traveling means coactive to indicate whether an internal thread nested on the least steep side face of the master thread is of acceptable minor 6@ diameter.

In testimony whereof I hereunto affix my si gnature.

WILLIAM E. HOKE. 

